STUDIES ON SOLUBILIZED ADENYLATE KINASE FROM MITOCHONDRIA

1966 ◽  
Vol 44 (11) ◽  
pp. 1469-1475 ◽  
Author(s):  
Marjorie A. Brewster ◽  
Ezzat S. Younathan
Keyword(s):  
Activation Energy ◽  
Rat Liver ◽  
Adenylate Kinase ◽  
Divalent Cations ◽  
Metabolic Function ◽  
Kcal Mole ◽  
Temperature Optimum ◽  
Ph Optimum ◽  
Sensitive Method

Adenylate kinase from mitochondria of rat liver was made soluble by sonication. The enzyme had a pH optimum of 8.0, temperature optimum of 30°, and activation energy of 12.2 kcal/mole. It was activated by several divalent cations in the following order of efficiency: Mg++ > Co++ > Mn++ > Ca++, with an optimal Mg++: ADP ratio of 1. The apparent Km value (ADP as substrate) was found to be 1.3 mM at pH 7.4 and 30°. The activity was sensitive to phloretin and mildly activated by aurovertin. Oligomycin, 2,4-dinitrophenol, p-chloromercuribenzoate, alloxan, and phlorizin had no effect on the activity. The metabolic function and a comparison of the properties of this solubilized mitochondrial adenylate kinase with those of similar preparations from other sources are discussed in the light of these findings. During this study, a sensitive method adaptable for a large number of assays of adenylate kinase was developed, and is described in detail.

Rat liver L-threonine deaminase: Properties and purification

1985 ◽  
Vol 5 (6) ◽  
pp. 499-508 ◽  
Author(s):  
R. Leoncini ◽  
R. Pagani ◽  
A. Casella ◽  
E. Marinello
Keyword(s):  
Thermal Stability ◽  
Rat Liver ◽  
Competitive Inhibitor ◽  
New Method ◽  
Optimum Temperature ◽  
Temperature Optimum ◽  
Threonine Deaminase ◽  
Ph Optimum ◽  
Carbonate Ions

A new method of purification of rat liver L-threonine deaminase has been developed, and the results obtained are compared with values obtained by other authors. Some properties of this enzyme (pH optimum, temperature optimum, thermal stability, specificity, etc.) have been examined and we found that the enzyme is inhibited by carbonate ions, that L-cysteine (a competitive inhibitor) is also an inactivator of the enzyme and that it is bound to the enzyme in a ratio of 0.25 mole of cysteine per mole of enzyme, supporting the hypothesis that the enzyme consists of 4 subunits.

Regulation of acetyl-CoA carboxylase by glucagon in HeLa cells

1985 ◽  
Vol 5 (6) ◽  
pp. 491-497
Author(s):  
R. P. Bhullar ◽  
K. Dakshinamurti
Keyword(s):  
Thermal Stability ◽  
Rat Liver ◽  
Hela Cells ◽  
Competitive Inhibitor ◽  
Acetyl Coa Carboxylase ◽  
Optimum Temperature ◽  
Temperature Optimum ◽  
Threonine Deaminase ◽  
Ph Optimum ◽  
Carbonate Ions

A new method of purification of rat liver L-threonine deaminase has been developed, and the results obtained are compared with values obtained by other authors. Some properties of this enzyme (pH optimum, temperature optimum, thermal stability, specificity, etc.) have been examined and we found that the enzyme is inhibited by carbonate ions, that L-cysteine (a competitive inhibitor) is also an inactivator of the enzyme and that it is bound to the enzyme in a ratio of 0.25 mole of cysteine per mole of enzyme, supporting the hypothesis that the enzyme consists of 4 subunits.

o-Succinylbenzoate: Coenzyme A Ligase, an Enzyme Involved in Menaquinone (Vitamin K2) Biosynthesis, Displays Broad Specificity

1991 ◽  
Vol 46 (7-8) ◽  
pp. 585-590 ◽  
Author(s):  
Hans-Jürgen Sieweke ◽  
Eckhard Leistner
Keyword(s):  
Coenzyme A ◽  
Divalent Cations ◽  
Vitamin K2 ◽  
Optimum Temperature ◽  
Temperature Optimum ◽  
Ph Optimum ◽  
Cofactor Specificity ◽  
Mycobacterium Phlei ◽  
Coenzyme A Ligase ◽  
Broad Specificity

o-Succinylbenzoate: coenzyme A ligase, an enzyme involved in menaquinone biosynthesis, was purified from Mycobacterium phlei and characterized with respect to isoelectric point, molecular weight, pH optimum, temperature optimum and kinetic data. The enzyme hydrolyses ATP to AMP. The substrate and cofactor specificity of the enzyme was tested with analogues of o-succinylbenzoic acid, different nucleotides, thiols and divalent cations. The enzyme appears to possess broad specificity for substrates and cofactors.

Purification and Properties of Rat Liver Nuclear Protein Kinases

1972 ◽  
Vol 50 (12) ◽  
pp. 1249-1259 ◽  
Author(s):  
P. R. Desjardins ◽  
P. F. Lue ◽  
C. C. Liew ◽  
A. G. Gornall
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinases ◽  
Rat Liver ◽  
Nuclear Protein ◽  
Kinase Inhibitor ◽  
Divalent Cations ◽  
Ph Optimum ◽  
Heat Stable ◽  
Low Concentrations

Two protein kinases, designated NI and NII, have been isolated from rat liver nuclei. These enzymes have a similar pH optimum and phosphorylate phosvitin and casein more readily than histone. Both enzymes require magnesium for activity. In the absence of Mg2+, other divalent cations such as Ca2+, Co2+, and Mn2+ can substitute partially for Mg2+ when the reaction is catalyzed by NI. With NII, only Co2+ showed any activity in the absence of Mg2+. Magnesium decreased the apparent Km for ATP of protein kinase NI without changing the Vmax of the reaction, and decreased the apparent Km's for both ATP and casein, while increasing the Vmax of the reaction threefold with protein kinase NII. Both enzymes are stimulated about twofold by low concentrations (0.1–0.3 M) of NaCl, KCl, and sodium acetate, whereas higher concentrations (> 0.5 M) inhibit their activities. Both enzymes are inhibited by low concentrations of NaF (0.02 M) and (NH4)2SO4 (0.1 M). NI and NII were found to have sedimentation coefficients of 3.6 S and 10.8 S, respectively. The nuclear protein kinases are not activated by cyclic AMP or cyclic GMP, and are not inhibited by the heat-stable cyclic AMP-dependent protein kinase inhibitor.

Dolichol and polyprenol kinase activities in microsomes from etiolated rye seedlings

1992 ◽  
Vol 70 (6) ◽  
pp. 455-459 ◽  
Author(s):  
Robert T. Rymerson ◽  
Kenneth K. Carroll ◽  
Jack W. Rip
Keyword(s):  
Rat Liver ◽  
Divalent Cations ◽  
Liver Microsomes ◽  
Microsomal Protein ◽  
Rat Liver Microsomes ◽  
Ph Optimum ◽  
Dolichyl Phosphate ◽  
Triton X ◽  
Enhance Activity ◽  
Better Than

Dolichol kinase activity in microsomes from etiolated rye seedlings had a pH optimum at 8 with a shoulder at pH 6.5. Triton X-100 (0.4%) was required for optimum activity. Exogenous divalent cations did not enhance activity, although Mg+2 was added routinely. Rye microsomes were found to contain dolichol and polyprenol in a ratio of 3 to 2. Rye, soybean embryo, and rat liver microsomes catalyzed the synthesis of 78, 52, and 516 nmol [14C]dolichyl phosphate/(mg microsomal protein∙h) compared with 21, 22, and 49 nmol [3H]polyprenyl phosphate/(mg microsomal protein∙h), respectively. It is clear that microsomes from plant systems can catalyze the phosphorylation of polyprenol better than rat liver when compared with their abilities to catalyze the phosphorylation of dolichol. It is not known whether one or more kinases is responsible for catalyzing the phosphorylation of these two closely related groups of compounds.Key words: dolichol, polyprenol, dolichyl phosphate, polyprenyl phosphate, kinases.

Biochemical studies on the production of neuraminidase by environmental isolates of Vibrio cholerae non-O1 from Bulgaria

2011 ◽  
Vol 57 (7) ◽  
pp. 606-610 ◽  
Author(s):  
Rumyana Eneva ◽  
Stephan Engibarov ◽  
Tanya Strateva ◽  
Radoslav Abrashev ◽  
Ignat Abrashev
Keyword(s):  
Vibrio Cholerae ◽  
Pathogenic Bacteria ◽  
Environmental Isolates ◽  
Anaerobic Conditions ◽  
Temperature Optimum ◽  
Ph Optimum ◽  
Cholera Vibrio ◽  
Key Factor ◽  
Aeration Conditions ◽  
The One

Neuraminidase is a key factor in the infectious process of many viruses and pathogenic bacteria. The neuraminidase enzyme secreted by the etiological agent of cholera — Vibrio cholerae О1 — is well studied in contrast with the one produced by non-O1/non-O139 V. cholerae. Environmental non-O1/non-O139 V. cholerae isolates from Bulgaria were screened for production of neuraminidase. The presence of the neuraminidase gene nanH was detected in 18.5% of the strains. Тhe strain showing highest activity (30 U/mL), V. cholerae non-O1/13, was used to investigate the enzyme production in several media and at different aeration conditions. The highest production of extracellular neuraminidase was observed under microaerophilic conditions, which is possibly related to its role in the infection of intestine epithelium, where the oxygen content is low. On the other hand, this is another advantage of the microbe in such microaerophilic environments as sediments and lake mud. The highest production of intracellular neuraminidase was observed at anaerobic conditions. The ratio of extracellular to intracellular neuraminidase production in V. cholerae was investigated. The temperature optimum of the enzyme was determined to be 50 °C and the pH optimum to be 5.6–5.8.

Biosynthesis of the Diguanosine Nucleotides. I. Purification and Properties of an Enzyme from Yolk Platelets of Brine Shrimp Embryos

1974 ◽  
Vol 52 (3) ◽  
pp. 231-240 ◽  
Author(s):  
A. H. Warner ◽  
P. C. Beers ◽  
F. L. Huang
Keyword(s):  
Molecular Weight ◽  
Brine Shrimp ◽  
Artemia Salina ◽  
Temperature Optimum ◽  
Small Molecular Weight ◽  
Ph Optimum ◽  
Optimal Activity ◽  
Purification And Properties

An enzyme that catalyzes the synthesis of P1P4-diguanosine 5′-tetraphosphate (Gp4G) has been isolated and purified from yolk platelets of encysted embryos of the brine shrimp, Artemia salina. The enzyme GTP:GTP guanylyltransferase (Gp4G synthetase) utilizes GTP as substrate, has a pH optimum of 5.9–6.0, a temperature optimum of 40–42 °C, and requires Mg2+ and dithiothreitol for optimal activity. The synthesis of Gp4G is inhibited markedly by pyrophosphate, whereas orthophosphate has no effect on the reaction. In the presence of GDP the enzyme also catalyzes the synthesis of P1,P3-diguanosine 5′-triphosphate (Gp3G), but the rate of synthesis is low compared with Gp4G synthesis and dependent upon other small molecular weight components of yolk platelets.

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

The slow oxidation of methane

1956 ◽  
Vol 235 (1201) ◽  
pp. 158-173 ◽  
Keyword(s):  
Activation Energy ◽  
Hydrogen Peroxide ◽  
Induction Period ◽  
Hydrofluoric Acid ◽  
Pressure Rise ◽  
Pressure Change ◽  
Kcal Mole ◽  
Gaseous Products ◽  
Oxidation Of Methane ◽  
Reproducible Manner

Mixtures of methane and oxygen behave in a reproducible manner at temperatures of 440 to 520°C and initial pressures of 100 to 350 mm when reacting in Pyrex vessels freshly cleaned with hydrofluoric acid. The apparent order of the reaction ranged from 2∙3 to 2∙6 and the overall activation energy from 29 to 41 kcal/mole. Analyses of the products formed have been made, together with measurements of pressure change. Formaldehyde is formed from the commencement of the reaction including the induction period, but its concentra­tion reaches a maximum near the stage where the pressure rise is a maximum, and then falls off. Hydrogen peroxide is also formed, less rapidly in the earliest stage, but its rate of formation overtakes that of formaldehyde and it reaches an even higher concentration. No other peroxides were detected, nor was methanol found. Hydrogen was present in the gaseous products. These observations are not in full accord with some of the conclusions derived from earlier investigations.

Temperature-induced alanine oxidation in a psychrotrophic Pseudomonas

1975 ◽  
Vol 21 (12) ◽  
pp. 2028-2033
Author(s):  
Prince K. Zachariah ◽  
John Liston
Keyword(s):  
Heat Treatment ◽  
Enzyme Synthesis ◽  
Optimum Temperature ◽  
Temperature Optimum ◽  
Ph Optimum ◽  
Sephadex Column ◽  
Oxidase System ◽  
Psychrotrophic Bacteria ◽  
Induction Of Enzymes ◽  
Elution Fraction

A psychrotrophic pseudomonad isolated from iced fish oxidized alanine at temperatures close to 0 °C and grew over the range 0 °C–35 °C. The rate of oxidation of alanine, measured manometrically, by cells grown at 2 °C was lower than that of cells grown at 22 °C. However, the consumption of oxygen after heat treatment at 35 °C for 35 min was reduced considerably by 2 °C grown cells. Alanine oxidase activity was tested in an extract from cells grown at 2 °C and 22 °C with alanine as the sole carbon, nitrogen, and energy source. Cells grown at 2 °C produced an alanine oxidase with a temperature optimum of 35 °C and pH optimum of 8, which lost about 80% activity by heat treatment at 40 °C for 30 min. There was no change in activity after dialysis at pH 7, 8, or 9. Extracts from cells grown at 22 °C contained an alanine oxidase system with an optimum temperature of 45 °C, a pH optimum above 8, and only about 30% reduction of activity after heat treatment. This enzyme activity was concentrated in the 0.5 M elution fraction from a Sephadex column, and dialysis reduced the activity at pH 7 and 8. Mesophilic enzyme synthesis apparently started around a growth temperature of 10 °C.The crude alanine oxidase systems of Pseudomonas aeruginosa derived from cells grown at 13 °C and 37 °C had a common optimum temperature of 45 °C. These data suggest that one mechanism of psychrophilic growth by psychrotrophic bacteria may be the induction of enzymes with low optimum temperatures in response to low temperature conditions.

Sign in / Sign up

Export Citation Format

Share Document